Search for ferroelectricity in fluoroperovskites: Comparison between LiNiF3 and NaNiF3

Abstract

Employing first-principles calculations, we have investigated the possible existence of the ferroelectric instability in the G-type antiferromagnetic NaNiF3 and LiNiF3 fluoroperovskites. The behavior of the unstable modes, at the cubic high-symmetry structure, is studied as a function of pressure. This study shows the vibrational landscape and define the conditions to drive the ferroelectricity in these materials, where the A-site dominates the polar instabilities.